Effects of Nitrogen Nutrition on Grain Quality in Upland Rice Zhonghan 3 and Paddy Rice Yangjing 9538 Under Different Cultivation Methods

For evaluating the differences between upland and paddy rice (Oryza sativa L.) as well as interaction between cultivation methods and nitrogen (N) levels, the upland rice cultivar Zhonghan 3 (japonica) and the paddy rice cultivar Yangjing 9538 (japonica) were planted in moist cultivation (MC) and bare dry-cultivation (DC). Each cultivar had 3 N-application treatments (100 kg−1 for low N, 200 kg−1 for normal N, and 300 kg−1 for high N) in MC and DC conditions. Compared with normal N treatment, HN reduced grain yield for both cultivars under DC and for the paddy rice cultivar under MC; whereas, it promoted the yield of upland rice under MC. With the increase of N application rate, the percentage of chalky grain and the chalkiness of upland rice increased under DC, however, the 2 indices were the largest in the normal N treatment and the smallest in the high N treatment under MC; for paddy rice, the percentage of chalky grains and the chalkiness showed a declined trend under DC but an in increased trend under MC. Under both MC and DC, the protein content enhanced in both upland and paddy rice when more N was applied, whereas the amylose content declined. The highest breakdown viscosity and the lowest setback viscosity were observed in upland rice treated with normal N and in paddy rice treated with low N. Compared with MC, DC improved the appearance quality and the nutrient quality of upland rice, and there was no significant variations in other quality indices between upland and paddy rice. The upland rice had better nutrient quality but poorer appearance and cooking qualities than paddy rice. The cooking and nutrient qualities showed lower correlations to the leaf N content in upland rice than paddy rice. These results suggest that the response of upland rice to cultivation method and N level is in great difference to that of paddy rice.